1. Field of the Invention
This invention relates to processes of treating metal surfaces with aqueous acidic compositions to increase the resistance to corrosion of the treated metal surface, either as thus treated or after subsequent overcoating with some conventional organic based protective layer, and to increase the adhesion of such a protective layer.
2. Statement of Related Art
A very wide variety of materials have been taught in the prior art for the general purposes of the present invention, but most of them contain hexavalent chromium or other inorganic oxidizing agents which are environmentally undesirable.